I don’t think it’s a coincidence that the truck in this article (and some of the links I’ve seen) are rentals. That leads me to believe these are not professional truck drivers doing it. The one time I witnessed a truck hitting an overpass, it was also a rental truck. People used to driving cars who sometimes drive a truck aren’t likely to consider this or think vague warnings are directed at them.
The one time I drove a rental truck across an area bridge, I pulled out the usual fee for cars and had it in hand when approaching the tollbooth. I offered it to the collector, and she gave me a blank look before explaining that I would need to pay a lot more than that! It never crossed my mind until that moment, and luckily I had enough extra cash to pay it.